The present invention relates to an electronic pressure switch having an axially displaceable electronic proximity switch member and a diaphragm carrying a metal plate, both the diaphragm and the plate being arranged perpendicularly to the axis of, and spaced from, the proximity switching unit, and a compression spring arranged coaxially around the proximity switch member and supported at one end on the metal plate.
In a known electronic pressure switch, a pressure medium acts on the side of the diaphragm remote from the compression spring so that with increasing pressure against the diaphragm and the metal plate, the spring is compressed. When a preselected setting pressure has been reached, the metal plate enters the switching, or sensing, range of the electronic proximity switch member. Such a switch member can be constructed to operate inductively and contains a thyristor which is thus activated and places a voltage across the output of the switch. When the pressure drops to below the preselected switch-on pressure, the thyristor opens so that the voltage across the switch output disappears again.
This electronic pressure switch is part of a control circuit in which the diaphragm is the measuring member and the electronic proximity switch member constitutes the regulating member. However, such a pressure switch can be used only for two-point regulation in which the switching on and off process occurs when a certain given pressure is passed.